USB: musb: fix CONFIGDATA register read issue

USB: musb: fix CONFIGDATA register read issue

INDEX register has to be set to '0' before reading
CONFIGDATA register which is only present in TI musb
platforms.

Currently the default register access mode is set to
FLAT_MODE thus INDEX register is not getting set
properly with musb_ep_select() which is just a nop
operation in FLAT_MODE.This invalid register read is
causing module reinset failure.

Fixing the issue by moving INDEX register write part to
musb_read_configdata() function itself.

Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>